We propose to continue to work on the synthesis of compounds which are potentially cytotoxic. Compounds to be investigated are alpha-fluoro amino acids, gabaculine analogs and cyclopropanone derivatives. The mechanisms of inhibition of S-adenosylhomocysteinase by 2'-deoxy-adenosine is also under investigation. 5'-deoxyadenosine has been found to be extremely cytotoxic to one liver cell line (H4S). The mechanism of this toxicity will be further pursued. Fluoroaspartate is extremely cytotoxic to certian cell lines. Some indications are available that it might inhibit or inactivate TRNA charging enzymes. We will continue an investigation of the mechanism of action of this compound.